woltereck



UNITED STATES PATENT OFFICE.

HERMAN C. YVOLTEREGK, OF NEW YORK, N. Y.

PROCESS OF MANUFACTURING WHITE LEAD.

SPECIFICATION forming part of Letters Patent No. 589,801, dated September 7, 1897.

Application filed April 9, 1897. Serial No. 631,449. (No specimens.)

To 0. whom it may concern:

Be it known that I, HERMAN C. WoLTEREcK, a citizen of the United States, residing at New York, in the county and State of New York, have invented certain new and useful Improvements in Processes of Manufacturing White Lead by Electrolysis, of which the following is a specification.

My invention relates to the manufacture of white lead by electrolysis; audit consists in certain novel methods of operation and in the application of certain electrochemical reactions, which permit the successful operation of a continuous process.

It is well known and has been practiced for a number of years that the electric current will decompose certain alkaline salts, so as to produce a soluble lead salt and a caustic alkali, which when mixed with the former will precipitate the same as a hydroxid, which may subsequently be converted into the hydrated carbonate of lead by treating the same with carbonic-acid gas. It has been observed, however, that the white lead thus obtained has not the same covering capacity as the white lead obtained by the old dry processes, as the precipitated hydroxid is more or less crystalline in character and does not change its form on being transformed into the hydrated carbonate. The processes of Kessler, United States Patent No. 292,119; Bottome, No. 414,935; Kytc, No. 459,946; Browne, No. 496,109; Browne and Chaplin, Nos. 551,361, 555,232, 563,553, and 563,555 describe such processes, none of which has been able to furnish a marketable quality of white lead.

My process consists in first producing a soluble salt of lead in the presence of nascent carbonic-acid gas and caustic alkali, by which process the hydrated carbonate of lead is formed in one reaction and yields a product of exceptional fineness.

For the purposes of my process I use an electrolyte composed of a ten to fifteen per cent. solution of a mixture of the salt, derived from an alkali and any acid which is able to form soluble lead salts, and the bicarbonate of an alkali, which will furnish the carbonic acid as required. The salts of acetic, sulfuric, nitric, hydrochloric, and Various other acids, in combination with an alkali, may be employed advantageously. I will illustrate the reactions which take place when a solution of the acetate and bicarbonate of soda is employed.

At the negative pole (anode) free acetic acid is formed, which dissolves the lead as acetate of lead, carbonic acid being set free there at the same time from the bicarbonate. At the positive pole (cathode) free caustic soda is formed, both from the acetate and bicarbonate of soda. As the liquid is constantly circulating by means of the bubbles of carbonic-acid gas introduced at the bottom of the vessel the solutions of acetate of lead and caustic soda come into contact in the presence of carbonic-acid gas and the following reactions take place:

Anode.

Cathode. SNaOH; 6H

III.

ZNaOI'lHQCO (supplied as gas):2NaOH.GO

the molecular weights in the reaction shown above.

I prefer to use the salts of ammonia, as these require only an electromotive force of 0.7 'volt, while the potassium and sodium salts require an average of four volts.

\Vhat I claim as new, and desire to secure by Letters Patent, is-

1. The process of producing white lead which consists in passing an electric current from an anode of metallic lead through an alkaline electrolyte consisting of a solution of a salt of ammonia in combination with any acid, which will produce a soluble lead salt (including sulfuric acid) and of a bicarbonate of an alkali to a cathode of lead, carbon or any other suitable material, thereby causing a decomposition of the salts in the electrolyte, and a formation of a soluble compound of lead, which is transformed into the hydrated carbonate of lead by the simultaneous generation of free carbonic acid at the said anode and by the presence of caustic alkali (ammonia) generated at said cathode, passing a current of carbonic-acid gas through said electrolyte to regenerate the spent alkaline bicarbonate until said anode is completely dissolved.

2. The process of producing white lead which consists in passing an electric current from an anode of metallic lead through an alkaline electrolyte consisting of a solution any other suitable material, thereby causing a decomposition of the salts in the electrolyte and formation of a soluble compound of lead, which is transformed into the hydrated carbonate of lead by the simultaneous generation of free carbonic acid at the said anode and by the presence of caustic alkali generated at said cathode, and passing a current of carbonic-acid gas through said electrolyte to regenerate the spent alkaline bicarbonate until said anode is completely dissolved, all for the purpose asset forth and described.

HERMAN C. VOLTEREOK.

lVitncsses: LOUIS TH. COHEN,

LILLIAN Fonn. 

